It is estimated that one out of eight women will face breast cancer at some point during her lifetime, and for women age 40-55, breast cancer is the leading cause of death. While methods for detecting and treating breast cancer initially were crude and unsophisticated, advanced instrumentation and procedures now are available which provide more positive outcomes for patients.
In the 1800s the only treatment for breast cancer was removal of the entire breast. Given that the sole method of detection and diagnosis was palpation, treatment was only directed when the breast tumor was well advanced. Modified radical mastectomies are still performed today for patients with invasive cancer, such a procedure involving the removal of the entire breast and some or all of the axillary lymph nodes. Radical or modified radical mastectomies involve serious trauma for the patient during surgery with the severest cosmetic results after surgery.
Another surgical option upon the discovery of malignant tumor is what is referred to as breast conserving surgery, which also is referred to as lumpectomy, tumorectomy, segmental mastectomy and local excision. Meant to address the cosmetic concerns associated with removal of the breast, only the primary tumor and a margin of surrounding normal breast tissue is removed. Determining the proper amount of tissue to be removed involves balancing the need to take sufficient tissue to prevent recurrence with the desire to take as little tissue as possible to preserve the best cosmetic appearance. A more limited nodal dissection now is performed with the primary purpose being staging rather than therapy. While an improvement over radical mastectomy, breast-conserving surgery still involves the removal of large sections of breast tissue. Risks associated with such surgery include wound infection, seroma formation, mild shoulder dysfunction, loss of sensation in the distribution of the intercostobrachial nerve, and edema of the breast and arm. For more information on invasive tumor therapy, see:
(1) Harris, Jay R., et al. "Cancer of the Breast." Cancer: Principles and Practices of Oncology, Fourth Edition. Eds. DeVita, et al. Philadelphia: J. B. Lippincott Co., 1993. 1264-1285. PA1 (2) Jobe, William E. "Historical Perspectives." Percutaneous Breast Biopsy. Eds. Parker, et al. New York: Raven Press, 1993. 1-5. PA1 (3) Rosen, Paul Peter. Rosen's Breast Pathology. Philadelphia: Lippincott-Raven Publishers, 1997. 837-858. PA1 (4) Parker, Steve H. "Needle Selection" and "Stereotactic Large-Core Breast Biopsy." Percutaneous Breast Biopsy. Eds. Parker, et al. New York: Raven Press, 1993. 7-14 and 61-79. PA1 (5) Parker, Steve H. "The Advanced Breast Biopsy Instrumentation: Another Trojan Hourse?" Am. J. Radiology 1998; 171: 51-53. PA1 (6) D'Angelo, Philip C., et al. "Stereotactic Excisional Breast Biopsies Utilizing the Advanced Breast Biopsy Instrumentation System." Am J Surg. 1997; 174: 297-302. PA1 (7) Ferzli, George S., et al. "Advanced Breast Biopsy Instrumentation: A Critique." J Am Coll Surg 1997; 185: 145-151.
Mastectomies and breast-conserving surgeries generally are procedures utilized for invasive tumor. Advances in tumor detection, however, have radically changed the course of diagnosis and treatment for a tumor. With the advent of imaging devices, such as the mammogram, suspect tumor may be located when it is of relatively small size. Today, tumor detection generally involves both a mammogram and a physical examination, which takes into account a number of risk factors including family history and prior occurrences. Technical improvements in mammogram imaging include better visualization of the breast parenchyma with less exposure to radiation, improvements in film quality and processing, improved techniques for imaging, better guidelines for the diagnosis of cancer and greater availability of well-trained mammographers. With these advancements in imaging technology, a suspect tumor may be detected which is 1 cm or smaller. More recently substantial progress has been witnessed in the technical disciplines of magnetic resonance imaging (MRI) and ultrasound imagining. With these advances, the location of a lesion is observable as diagnostic/analytic or therapeutic procedures are carried out.
In the past, because a tumor normally was not discovered until it had reached an advanced stage, the issue of whether a tumor was malignant or benign did not need to be addressed. With the ability to locate smaller areas of suspect tumor, this issue becomes of critical importance, particularly in light of the fact that only 20% of small, non-invasive tumors are malignant. Tumors identified as being benign may be left in situ with no excision required, whereas action must be taken to excise suspect tissue confirmed to be malignant. In view of the value of classifying a tumor as malignant or benign, breast biopsy has become a much-utilized technique with over 1 million biopsies being performed annually in the United States. A biopsy procedure involves the two step process of first locating the tumor then removing pall or all of the suspect tissue for examination to establish precise diagnosis.
One biopsy option available upon detection of a suspect tumor is an open surgical biopsy or excisional biopsy. Prior to surgery, a radiologist, using mammography, inserts a wire into the breast to locate the tumor site. Later during surgery, the surgeon makes an incision in the breast and removes a large section of breast tissue, including the suspect tissue and a margin of healthy tissue surrounding the tumor. As with other similar procedures, such as those described above, open surgery may result in high levels of blood loss, scarring at the location of the incision and permanent disfigurement, due to the removal of relatively large amounts of tissue. Because of the critical prognostic significance of tumor size, the greatest advantage of the excisional biopsy is that the entire area of the suspect tumor is removed. After being removed and measured, the specimen is split by a pathologist in a plane that should bisect a tumor if present, then the margin between tumor and healthy tissue is examined. Microscopic location of carcinoma near the margin provides information for future prognosis. Thus the pathology laboratory is oriented to the morphological aspect of analysis, i.e. the forms and structures of involved tissue.
For information on pathology of breast biopsy tissue, see:
Other less invasive options are available which avoid the disadvantages associated with open surgery. One such non-invasive option is that of needle biopsy, which may be either fine needle aspiration or large core. Fine needle aspiration (FNA) is an office procedure in which a fine needle, for example of 21 to 23 gauge, having one of a number of tip configurations, such as the Chiba, Franzeen or Turner, is inserted into the breast and guided to the tumor site by mammography or stereotactic imaging. A vacuum is created and the needle moved up and down along the tumor to assure that it collects targeted cellular material. Generally, three or more passes will be made to assure the collection of a sufficient sample. Then, the needle and the tissue sample are withdrawn from the breast.
The resulting specimen is subject to a cytologic assay, as opposed to the above-noted morphological approach. In this regard, cell structure and related aspects are studied. The resultant analysis has been used to improve or customize the selection of chemotherapeutic agents with respect to a particular patient.
While a fine needle aspiration biopsy has the advantages of being a relatively simple and inexpensive office procedure, there are some drawbacks associated with its use. With fine needle aspiration, there is a risk of false-negative results, which most often occurs in cases involving extremely fibrotic tumor. In addition, after the procedure has been performed there may be insufficient specimen material for diagnosis. Finally, with fine needle aspiration alone the entire area of suspect tissue is not removed. Rather, fragmented portions of tissue are withdrawn which do not allow for the same type of pathological investigation as the tissue removed during an open surgery biopsy.
This limitation also is observed with respect to large core needle biopsies. For a large core needle biopsy, a 14 to 18 gauge needle is inserted in the breast having an inner trocar with a sample notch at the distal end and an outer cutting cannula. Similar to a fine needle aspiration, tissue is drawn through the needle by vacuum suction. These needles have been combined with biopsy guns to provide automated insertion that makes the procedure shorter and partially eliminates location mistakes caused by human error. Once inserted, multiple contiguous tissue samples may be taken at a time.
Samples taken during large core needle biopsies may be anywhere from friable and fragmented to large pieces 20 to 30 mm long. These samples may provide some histological data, unlike fine needle aspiration samples, however, they still do not provide the pathological information available with an open surgical biopsy specimen. Further, as with any mechanical cutting device, excessive bleeding may result during and following the procedure. Needle biopsy procedures are discussed in:
A device which is somewhere between a needle biopsy and open surgery is referred to as the Advanced Breast Biopsy Instrumentation (ABBI). With the ABBI procedure, the practitioner, guided by stereotactic imaging, removes a core tissue sample of 5 mm to 20 mm in diameter. While the ABBI has the advantage of providing a large tissue sample, similar to that obtained from an open surgical biopsy, the cylindrical tissue sample is taken from the subcutaneous tissue to an area beyond the suspect tumor. For tumors embedded more deeply within the breast, the amount of tissue removed is considerable. In addition, while less expensive than open surgical biopsy, the ABBI has proven expensive compared to other biopsy techniques, and it has been noted that the patient selection for the ABBI is limited by the size and location of the tumor, as well as by the presence of very dense parenchyma around the tumor. For discussion on the ABBI, see:
Another biopsy device has been referred to as the Minimally Invasive Breast Biopsy (MIBB). This carries out a vacuum-assisted core biopsy wherein fragments of suspect tissue are removed with an 8 gauge needle. While being less invasive, the MIBB yields only a fragmentary specimen for pathological study. The MIBB therefore is consistent with other breast biopsy devices in that the degree of invasiveness of the procedure necessarily is counterbalanced against the need for obtaining a tissue sample whose size and margins are commensurate with pathology requirements for diagnosis and treatment.
With all of the above diagnostic specimen collection and therapeutic removal procedures, opportunity exists for a seeding metastasis of healthy tissue with instrument borne malignant cells. Such activity typically will occur as an instrument or needle is removed from engagement with a malignant tumor.